Make sure we never pass a null Frame to Document::canNavigate()

Source/core/frame/Frame.h

Index: Source/core/frame/Frame.h
diff --git a/Source/core/frame/Frame.h b/Source/core/frame/Frame.h
index 5a78fa5477528314f7001e22b8fd6b7ee17469ce..72d5afda33fa7a5a756f3d5a2bae599e43eee36a 100644
--- a/Source/core/frame/Frame.h
+++ b/Source/core/frame/Frame.h
@@ -142,6 +142,18 @@ inline FrameTree& Frame::tree() const
     return m_treeNode;
 }
 
+// Allow equality comparisons of Frames by reference or pointer, interchangeably.

[eseidel, 2014/06/02 05:20:27]

Can we make this a macro?  Seems silly to have to type this out.

[Inactive, 2014/06/02 12:16:37]

Makes sense. We already duplicate this for several classes. Will do (likely in a
separate patch for clarity).

+inline bool operator==(const Frame& a, const Frame& b) { return &a == &b; }
+inline bool operator==(const Frame& a, const Frame* b) { return &a == b; }
+inline bool operator==(const Frame* a, const Frame& b) { return a == &b; }
+inline bool operator!=(const Frame& a, const Frame& b) { return !(a == b); }
+inline bool operator!=(const Frame& a, const Frame* b) { return !(a == b); }
+inline bool operator!=(const Frame* a, const Frame& b) { return !(a == b); }
+inline bool operator==(const PassRefPtr<Frame>& a, const Frame& b) { return a.get() == &b; }
+inline bool operator==(const Frame& a, const PassRefPtr<Frame>& b) { return &a == b.get(); }
+inline bool operator!=(const PassRefPtr<Frame>& a, const Frame& b) { return !(a == b); }
+inline bool operator!=(const Frame& a, const PassRefPtr<Frame>& b) { return !(a == b); }
+
 } // namespace WebCore
 
 #endif // Frame_h